Stringent security will surround the shifting of New Zealand's founding document, the Treaty of Waitangi, a few hundred metres up the road to the National Library.

The decision to shift the Treaty and other constitutionally significant documents from Archives New Zealand has sparked criticism by Labour after the cost was revealed at close to $7 million.

Chief archivist and general manager of Archives New Zealand, Greg Goulding, yesterday admitted it had caused some rumbles among staff, especially those who led tours and had worked alongside the document for many years.

An email from Mr Goulding to staff obtained by Labour MP Grant Robertson refers to those rumbles – and acknowledges that not everyone at Archives agreed shifting the Treaty was "a great idea".

"For those of us who work with these taonga on a regular basis and have come to strongly identify with them and their connection with us through being in the same space there may well be a sense of loss and sadness about this move."

Mr Goulding acknowledged yesterday some staff were "attached" to the documents and that was natural.

But he said there were compelling reasons for the move, including a higher profile building and the ability to accommodate more visitors than the current 10,000 people a year who make the trip to see the Treaty.

"We will be able to use some new technology and better designed display cases to enable people to see them more easily."

Labour has questioned why the Government is paying nearly $7m to move the Treaty and other documents, rather than pay $1m or $2m upgrading archives.

But Mr Goulding said that would pay for equipment to be upgraded but would not create extra capacity for visitors. "These are ... extremely important documents, an important part of our history and I think it's important New Zealanders have got a better opportunity to see them."

The Treaty, which is spread over nine documents, was previously housed at the Reserve Bank because of security threats, but was shifted to Archives New Zealand when those threats eased.

Mr Goulding confirmed security would be stringent when the documents were moved, probably late next year.

GIANT MURAL HAS TO MAKE WAY

A large mural once considered a safety hazard because of its metal spikes has been moved aside to make way for the Treaty of Waitangi.

The nine-metre-long mural, by Wellington artist John Drawbridge, has hung in the National Library since 1985, but is now in storage and will stay there until a buyer is found.

The National Library has confirmed there is no longer room for the mural now that it has to accommodate documents from Archives New Zealand, including the 1840 Treaty document.

Son Cameron Drawbridge said there were "no bad feelings" about his father's mural being moved, but he hoped it would eventually be returned to a public space.

He was not aware it was because of the Treaty document being moved there, but knew "space is precious".

"It's just a shame that it couldn't stay there because it was a good space for it. But it's just the size of it."

Many of his father's murals were large, including a 20m one from the secure reading room of the Archives building that has been bought by Victoria University, he said.

National Library public programmes manager Peter Rowlands said that, with historical documents being moved into its purpose-built room in the refurbished Molesworth St building in 2013, there was no wall space for the Drawbridge piece, known as National Library Mural 1970.

Negotiations were under way with three cultural and heritage agencies to transfer ownership of the mural.

A metal barrier was erected around the mural in 2002 after staff developed concerns about the 50-centimetre metal pins that protruded from it. The barrier was removed after a child was injured while swinging from it.